Moving TargetThis article is inspired by a question I received through Facebook; "Why do we have to rotate one of the subwoofers in an inverted stack cardioid array? Can't we achieve the same effect with all subwoofers facing the same direction and delay only?"

Well, not that I'm aware of. The problem with delay is that it results in a moving target.

A simple system that will allow you to calculate with decibels on the back of an envelope without having to use an actual calculator.

Coherence and reverberationCoherence is a common feature found on many analyzers enabling us to distinguish signal from measurement contamination. It will indicate whether you're measuring a loudspeaker or, e.g., the noise produced by a moving light.

Coherence is subject to change. One of the aspects involved (among others) that we’ll explore in-depth, is the relationship between the direct sound of a loudspeaker in a room and the room’s reverberation.

efficiency quotes anquotes 696x374For good cancellation behind inline cardioid subwoofer arrays like end-fire and gradient, it's mission critical that the subwoofers have matched levels. But how does the physical displacement between the subwoofers affect the array's performance over distance?

Prof. John VanderkooyProf. John VanderkooyIn 2010 Prof. John Vanderkooy presented an AES paper offering analytical proof and compelling evidence that the acoustic center for low frequencies resides in front of the loudspeaker at a distance of approximately two-thirds of the baffle radius.